U.S. Pat. No. 5,804,676 describes a process for preparing a polymer from a monomer mixture comprising 75% by weight or more of methyl methacrylate and 25% by weight or less of an alkyl acrylate in a homogeneous solution state in the presence of a polymerization initiator and a chain transfer agent. The polymerizate may contain 5-55% by weight of the monomer and 5 to 65% by weight of the solvent. The polymerizate containing volatiles is directly fed to a feed opening of an extruder having a barrel, a screw and a plurality of vents and the barrel being at a temperature of 170 to 270° C. The polymerizate is extruded through the extruder while substantially all volatiles are separated and recovered through a first vent of the extruder and remaining volatiles are separated through being removed trough at least one other vent disposed downstream of the first vent. The thermal decomposition rate is 3.0% by weight or less.
EP 0 694 565 A describes a process for the homogeneous polymerization of water insoluble polymers containing greater than 50% by weight of monomers selected from the group consisting of C1-C18 alkyl acrylate or methacrylate esters, N-substituted acryl or methacrylamides and mixtures thereof in substantially non-aqueous solutions. Water soluble polymerization initiators like for instance ammonium persulfate are dissolved in a sufficient amount of water whereby the amount of water does not exceed 25% by weight of the total solution. The polymers prepared by this process are devoid of undesirable initiator decomposition by-products.
U.S. Pat. No. 4,737,357 describes an aqueous dispersion of a water swellable but water-insoluble polymer formed between a quaternary ammonium monomer and a nonionic monomer. The copolymers described may be of the type EUDRAGIT® RS or EUDRAGIT® RL. It is generally mentioned that these kinds of copolymers may be produced by bulk polymerization or by solution or precipitation polymerization in an organic solvent, the polymer formed then being isolated from the solvent.
WO 2007/082868A1 relates to processes for preparing polymers which contain 50-90% by weight of at least one ester of (meth)acrylic acid, 5-50% by weight of at least one olefinically unsaturated, free-radically polymerizable anionogenic or anionic compound and further free-radically polymerizable compound in copolymerized form, by free-radical polymerization in a solution comprising alcohol, wherein the polymerization initiator used is at least one water-soluble initiator.
WO 2007/113129A1 relates to processes for preparing polymers by free-radical polymerization in a solution, which is characterized in that the polymerization initiator used is an ethanol-soluble initiator and the solution polymerization is performed in an alcoholic solvent which contains from 5 to 50% by weight of water.
CN 101475662A relates to a process for preparing polymethacrylamide ester of low membrane forming temperature and moderate permeability for pharmaceutical use. Such a polymer may be composed from ethyl acrylate, butyl acrylate, methyl methacrylate and trimethylammoniumethyl methacrylate chloride. The monomer composition to be polymerized is dissolved in comparably small amounts of solvents, 5-15% by weight.